Double-Structure Fiber-Reinforced Side Sill for Collision Stress Dispersion
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Solution Overview
Problem
Fiber-reinforced resins like CFRP have low ductility, leading to stress concentration and potential breakage of the coupling portion between the center pillar and side sill during a side collision.
Innovation Solution
A double-structured side sill made of fiber-reinforced resin with an outer and inner tubular member, featuring ridge and coupling surface portions, and recessed inner surfaces to disperse stress and enhance energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a fiber-reinforced resin side sill is used to reduce vehicle body weight, then weight reduction is achieved, but the low ductility of the material causes stress concentration and potential breakage at the coupling portion during side collision
Solution Approach 1:
The side sill is divided into multiple coupling portions along its length, each capable of independently deforming and absorbing energy. This segmentation prevents stress concentration at a single coupling portion, allowing the fiber-reinforced resin to maintain reliability while achieving weight reduction.
Solution Approach 2:
The coupling portions are designed with specific local structural characteristics that enhance their ability to deform and absorb energy. This local quality modification allows the rigid fiber-reinforced resin to exhibit controlled deformation behavior at critical locations, preventing breakage while maintaining overall structural integrity.
2Ease of manufacture
If the side sill structure is simplified to reduce manufacturing complexity, then ease of manufacture improves, but the ability to disperse stress and absorb energy during collision is reduced
Solution Approach 1:
The cross-sectional shape parameters of the side sill are optimized to create coupling portions that naturally deform and absorb energy during collision. By adjusting geometric parameters rather than adding complex structural elements, the design achieves improved reliability while maintaining manufacturing simplicity.
Data Source
AI summary
A side sill includes a double structure that is made of a fiber-reinforced resin and that includes an outer peripheral tubular member and an inner peripheral tubular member extending in a front-back direction of a vehicle body of a vehicle. The outer peripheral tubular member and the inner peripheral tubular member extend in a front-back direction of a vehicle body. The inner peripheral tubular member includes ridge portions and coupling surface portions. The ridge portions each extend in the front-back direction of the vehicle body. The coupling surface portions are each formed between corresponding two of the ridge portions adjacent to each other around an axis. The inner peripheral tubular member is provided over at least a region to which the lower portion of the center pillar is coupled.